Abstract

INTRODUCTION: While it is known that Black women are more likely to get triple negative breast cancer (TNBC) which carries a poor prognosis, it is less clear whether race affects outcome in this subtype independent of other factors. We sought to determine, in a national database, the relative impact of race and socioeconomic status on overall survival in women diagnosed with TNBC.

METHODS: The National Cancer Database was queried to determine factors affecting overall survival of patients diagnosed with TNBC between 2004 and 2013. Kaplan-Meier and Cox proportional hazards models were performed using SPSS Version 21.

RESULTS: 64,839 patients with TNBC (excluding other malignancies) were included in the analysis. Median patient age was 57 (range; 19-90). Of these, 47,124 (72.7%) were white, and 14,541 (22.4%) were black. Black women were more likely to be uninsured (5.2% vs. 3.0%, p<0.001) and in the lowest household income quartile (<$38,000; 39.9% vs. 13.7%, p<0.001). In addition, blacks were less likely to present with Stage 1 disease (31.6% vs. 41.2%, p<0.001), and more likely to have high grade tumors (85.3% vs. 80.2%, p<0.001). On average, blacks also had a longer time interval between diagnosis and initiation of treatment (34 vs. 28 days, p<0.001). Blacks had a mean overall survival of 94 months, compared to 98 months for whites (p<0.001). On multivariate Cox regression modelling controlling for age, stage, grade, time to first treatment, income, insurance status, comorbidities (measured by Charlson score), and region, race was no longer predictive of overall survival in patients with TNBC (black vs. white OR: 1.04; 95% CI: 0.98-1.11, p=0.199). Patients with private insurance were significantly less likely to die than those who were uninsured (OR: 0.66; 95% CI: 0.59-0.75, p<0.001) independent of other factors. Similarly, those in the highest income quartile were less likely to die than those in the lowest (OR: 0.79; 95% CI: 0.73-0.85, p<0.001). Patient age (p<0.001), stage (p<0.001), grade (p<0.001), region (p<0.001), Charlson score (p<0.001) and time to treatment (p=0.001) all remained significant in the model.

CONCLUSION: While black race is associated with higher stage and grade disease, longer time to treatment and lower socioeconomic status, when controlling for these factors, race does not independently affect overall survival in women with TNBC. Disparities in breast cancer outcomes in this population therefore appear to be mediated more by socioeconomic factors than by race alone.